When a camera is taking an image with LED flash the illumination of an object is most often a mix of a flash and an ambient light. Colors of the image captured by the camera are affected by ambient light type (fluorescent, incandescence, etc.), but also by the level of the ambient light compared to the flash light. The amount of reflected flash light from the object back to the camera depends mostly on flash efficiency, object reflectance and especially on a distance from the object to the flash, because the luminance follows inverse square law: it varies in inverse proportion to the square of distance.
Furthermore, the characteristics of images acquired by the camera depend on the spectral content (or the color temperature) of the light. When the spectral content of the flash is fixed, the desired image characteristics can be achieved by mounting color filters on the lens of the camera. However, this provides only limited control of image characteristics because the filters do not provide continuous control of the spectral content of the light received by the camera. In addition, the filters are inconvenient to use because to achieve different spectral filtering, the filters must be physically interchanged.
In case of some LED flashes, it is possible to turn the flash on for such a long time that camera AE (Auto Exposure) and AWB (Auto White Balance) control can adjust the exposure and color compensation gains to an optimum. The problems with that are increased power consumption, shortened lifetime of LED flash (result of heating) and longer delay between user's shutter-key press and actual image capturing. Also, most humans do not feel comfortable when a very bright light is pointing to their eyes, for example, for half a second.
Also, some cameras try “to guess” the best exposure and white balance settings before the flash is fired so that flash power consumption and capture delays are minimized. The problem is that it is difficult to calculate the settings if the distance and reflectance of the target object are not known.